1 / 61

Energy Efficient Process Heating

Energy Efficient Process Heating. Energy Balance on Furnace. Energy Saving Opportunities From Energy Balance. Reduce opening losses: radiation and air exchange Reduce cooling losses Reduce conveyance losses Reduce storage losses Reduce wall losses Reduce flue losses

tambre
Download Presentation

Energy Efficient Process Heating

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Energy Efficient Process Heating

  2. Energy Balance on Furnace

  3. Energy Saving Opportunities From Energy Balance • Reduce opening losses: radiation and air exchange • Reduce cooling losses • Reduce conveyance losses • Reduce storage losses • Reduce wall losses • Reduce flue losses • Improve internal heat transfer • Reduce air leakage into furnace • Control combustion air / oxygen • Reclaim heat • Pre-heat combustion air • Pre-heat load • Cascade heat to lower temperature processes

  4. Reduce Opening Losses

  5. Reduce Radiation Losses: ‘Room’ for Improvement

  6. Reduce Radiation Losses: ‘Better’

  7. Cover Charge Wells • 2 ft x 4 ft open charge well radiates and convects heat • Cover charge well with mineral fiber insulation 75% of time • Savings = $1,500 /yr

  8. Preheating Ladles: Too Much Space

  9. Preheating Ladles: Nice Tight Fit

  10. Reducing Air Exchange in Continuous Ovens By Modifying Entrance/Exit

  11. Reduce Cooling Losses

  12. Reduce Conveyance Losses • Slow conveyor • Brazing oven at 1,900 F • Conveyor runs at 0.7 ft/min • Conveyor loaded 30% of time • Slow conveyor to 0.3 ft/min when unloaded • Reduces conveyor losses by 40%

  13. Reduce Conveyance Losses Lighter conveyance fixtures reduce energy carryout losses

  14. Reduce Storage Losses Larger batch sizes to reduce number of loads in heat treat ovens

  15. Reduce Storage Losses Reduce bricks (thermal mass) on transport cars

  16. Reduce Storage Losses Increase batch sizes in arc furnaces

  17. Reduce Wall / Surface Losses

  18. Insulate Hot Surfaces • Insulate four lids at 400 F • Induction furnace efficiency = 51% • Savings = $17,0000 /yr

  19. Insulate Extruder Barrels

  20. Turn Off Heat When Not in Use

  21. Reduce Flue Losses

  22. Flue Losses • Flue losses increase with: • Temperature • Flow

  23. Reduce Flue Losses • Reduce Temperature • Improve internal heat transfer • Reduce Flow • Reduce air leakage into furnace • Combustion air control • Use O2 instead of ambient air for combustion

  24. Counter Flow Heat Transfer Reduces Exhaust Temperature T Q Parallel Flow x T Q Counter Flow x

  25. Convert Batch Cross Flow Processesto Continuous Counter Flow Batch crucible melting Counter-flow cupola melting

  26. Replace Reverb (Cross Flow) with Stack (Counter Flow) Furnace and Pre-heat Charge Reverb Furnace Stack Furnace

  27. Lead Melt Furnace: Place Scrap on Top and Drain Molten Lead From Bottom

  28. Molten Glass Transport:Each Exhaust Port Is A Zone

  29. Relocate Exhaust Portsto Increase Counter-flow Within Zones Increases convection heat transfer by 83% Contact length = 2 x (5 + 4 + 3 + 2 + 1) = 30 feet Contact length = (10 + 9 + 8 + 7 + 6 + 5 + 4 + 3 + 2 + 1) = 55 feet

  30. Set Exhaust Dampers to Increase Counter Flow in Dry Off Oven Product In Product Out 100% open 75% open 50% open 25% open 12% open

  31. Set Exhaust Dampers to Increase Counter Flow in Tile Kiln Tile Exit Tile Entrance

  32. Reduce Flue Flow

  33. Reduce Air Leakage Heat in Flue Gases Negative Pressure Combustion Air Air Leaks Fuel

  34. Seal Furnace Openings Seal opening around lid with mineral fiber blanket

  35. Flue damper Counterweight Hydraulic cylinder Hydraulic power unit Controller Compensating line Pressure tap (not in line with opposing burner) Use Draft Control to Balance Pressure

  36. Reduce Flue Flow: Control Combustion Air

  37. Combustion with Air Minimum Combustion Air (Stoichiometric): CH4 + 2 (O2 + 3.8 N2) CO2 + 2 H2O + 7.6 N2 Excess Combustion Air: CH4+ 4 (O2 + 3.8 N2) CO2 + 2 H2O + 15.2 N2 + 2 O2

  38. Excess Combustion AirDecreases Flame Temperature and Efficiency Air Preheat temperature) % Available Heat % Excess Air (% O2) in flue gases Flue gas temperature)

  39. Reduce Excess Air To 10% or CO Limit

  40. Reduce Flue Flow: Replace Air with Oxygen

  41. Combustion with Oxygen Eliminates Unnecessary Nitrogen • Combustion with Air • CH4 + 2 (O2 + 3.8 N2) > CO2 + 2 H2O + 7.6 N2 • Mair / Mfuel= [ (4 x 16) + (4 x 3.8 x 14) ] / (12 + 4) • Mair / Mfuel= 17.6 • Combustion with O2 • CH4 + 2 O2 > CO2 + 2 H2O • Mo2 / Mfuel = (4 x 16) / (12 + 4) • Mo2/ Mfuel= 4.0

  42. Combustion with Oxygen Increases Flame Temperature

  43. Combustion with Oxygen Increases Efficiency

  44. Reclaim Heat • Preheat combustion air • Preheat load/charge • Cascade to lower temperature process

  45. Preheat Combustion Air with External Recuperator

  46. ex. gas out Th2 = 950 F comb. air out Tc2 = 615 F comb. air in Tc1 = 95 F ex. gas in Th1 = 1,465 F Preheat Combustion Air with External Recuperator

  47. Preheat Combustion Airwith External Recuperator

  48. Preheat Combustion Air with Bayonet Recuperator

  49. Preheat Combustion Air with Tube-in-Tube Heat Exchanger

  50. Preheat Combustion Air with Regenerators

More Related